Array driven fabric performance notifications for multi-pathing devices

ABSTRACT

A host device is configured to communicate over a network with a storage system. The host device comprises a multi-path input-output (MPIO) driver configured to control delivery of input-output (IO) operations from the host device to the storage system over selected ones of a plurality of paths through the network. The MPIO driver is further configured to send one or more requests to the storage system for data corresponding to performance of one or more switch fabrics in the network, and to receive the data corresponding to the performance of the one or more switch fabrics from the storage system. The MPIO driver is also configured to identify one or more performance issues associated with at least one of the selected ones of the plurality of paths based on the received data, and to manage one or more of the input-output operations responsive to the identified performance issues.

FIELD

The field relates generally to information processing systems, and more particularly to storage in information processing systems.

BACKGROUND

Storage arrays and other types of storage systems are often shared by multiple host devices over a network. Applications running on the host devices each include one or more processes that perform the application functionality. The processes issue input-output (IO) operations for delivery to storage ports of the storage system. The storage ports are typically limited in number and each has limited resources for handling IO operations received from the host devices. Different ones of the host devices can run different applications with varying workloads and associated IO patterns. Such host devices also generate additional IO operations in performing various data services such as replication and migration so as to meet business continuity requirements.

Fibre channels can achieve lossless data transfer by utilizing buffer to buffer credit mechanisms. However, the Fibre channels are not immune to fabric congestion. When fabric congestion occurs, some host device multi-pathing software is not provided with sufficient information about the congestion situation. As a result, host device multi-pathing software is not equipped with necessary information to overcome the congestion.

SUMMARY

Illustrative embodiments configure a multi-path layer of one or more host devices to include functionality for receiving and processing fabric performance data from a storage array. For example, some embodiments include techniques for enabling host device multi-pathing software to receive fabric performance impact notification (FPIN) data from a storage array and structure IO operations to address and overcome fabric congestion issues.

In one embodiment, an apparatus comprises a host device configured to communicate over a network with a storage system. The host device comprises an MPIO driver configured to control delivery of IO operations from the host device to the storage system over selected ones of a plurality of paths through the network. The MPIO driver of the host device is further configured to send one or more requests to the storage system for data corresponding to performance of one or more switch fabrics in the network, and to receive the data corresponding to the performance of the one or more switch fabrics from the storage system. The MPIO driver is also configured to identify one or more performance issues associated with at least one of the selected ones of the plurality of paths based on the received data, and to manage one or more of the input-output operations responsive to the identified one or more performance issues.

These and other illustrative embodiments include, without limitation, apparatus, systems, methods and computer program products comprising processor-readable storage media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an information processing system configured with functionality in a multi-path layer of a host device for receiving and processing fabric performance data from a storage array in an illustrative embodiment.

FIG. 2 is a flow diagram of a process for receiving and processing fabric performance data from a storage array in an illustrative embodiment.

FIG. 3 is a block diagram showing multiple layers of a layered system architecture that includes a multi-path layer with functionality for receiving and processing fabric performance data from a storage array in an illustrative embodiment.

FIG. 4 is a flow diagram of a process for receiving fabric notifications and communicating with a host device on a storage array side.

FIG. 5 is a flow diagram of a process for receiving fabric notifications from a storage array and addressing fabric issues on a host device side.

DETAILED DESCRIPTION

Illustrative embodiments will be described herein with reference to exemplary information processing systems and associated computers, servers, storage devices and other processing devices. It is to be appreciated, however, that embodiments of the present disclosure are not restricted to use with the particular illustrative system and device configurations shown. Accordingly, the term “information processing system” as used herein is intended to be broadly construed, so as to encompass, for example, processing systems comprising cloud computing and storage systems, as well as other types of processing systems comprising various combinations of physical and virtual processing resources. An information processing system may therefore comprise, for example, at least one data center that includes one or more clouds hosting multiple tenants that share cloud resources. Numerous other types of enterprise and cloud-based computing and storage systems are also encompassed by the term “information processing system” as that term is broadly used herein.

FIG. 1 shows an information processing system 100 configured in accordance with an illustrative embodiment. The information processing system 100 comprises a plurality of host devices 102-1, 102-2, . . . 102-N. The host devices 102 communicate over a storage area network (SAN) 104 with at least one storage array 105. The storage array 105 comprises a plurality of storage devices 106-1, . . . 106-M each storing data utilized by one or more applications running on one or more of the host devices 102. The storage devices 106 are illustratively arranged in one or more storage pools. The storage array 105 and its associated storage devices 106 are an example of what is more generally referred to herein as a “storage system.” This storage system in the present embodiment is shared by the host devices 102, and is therefore also referred to herein as a “shared storage system.” Other embodiments can include only a single host device, possibly configured to have exclusive use of the storage system.

The host devices 102 illustratively comprise respective computers, servers or other types of processing devices capable of communicating with the storage array 105 of the SAN 104. For example, at least a subset of the host devices 102 may be implemented as respective virtual machines of a compute services platform or other type of processing platform. The host devices 102 in such an arrangement illustratively provide compute services such as execution of one or more applications on behalf of each of one or more users associated with respective ones of the host devices 102.

The term “user” herein is intended to be broadly construed so as to encompass numerous arrangements of human, hardware, software or firmware entities, as well as combinations of such entities.

Compute and/or storage services may be provided for users under a Platform-as-a-Service (PaaS) model, an Infrastructure-as-a-Service (IaaS) model and/or a Function-as-a-Service (FaaS) model, although it is to be appreciated that numerous other cloud infrastructure arrangements could be used. Also, illustrative embodiments can be implemented outside of the cloud infrastructure context, as in the case of a stand-alone computing and storage system implemented within a given enterprise.

The storage devices 106 of the storage array 105 of SAN 104 implement LUNs configured to store objects for users associated with the host devices 102. These objects can comprise files, blocks or other types of objects.

As used herein, the term “server” is to be broadly construed, and may encompass a host device, such as, for example, host device 102-1, a portion of a host device or a processing device separate from a host device.

The host devices 102 interact with the storage array 105 utilizing read and write commands as well as other types of commands, such as, for example, log select and log sense commands described further herein, that are transmitted over the SAN 104. Such commands in some embodiments more particularly comprise Small Computer System Interface (SCSI) commands, although other types of commands can be used in other embodiments. A given IO operation as that term is broadly used herein illustratively comprises one or more such commands. References herein to terms such as “input-output” and “10” should be understood to refer to input and/or output. Thus, an IO operation relates to at least one of input and output.

Also, the term “storage device” as used herein is intended to be broadly construed, so as to encompass, for example, a logical storage device such as a LUN or other logical storage volume. A logical storage device can be defined in the storage array 105 to include different portions of one or more physical storage devices. Storage devices 106 may therefore be viewed as comprising respective LUNs or other logical storage volumes.

Each of the host devices 102 illustratively has multiple paths to the storage array 105, with at least one of the storage devices 106 of the storage array 105 being visible to that host device on a given one of the paths. A given one of the storage devices 106 may be accessible to the given host device over multiple paths.

Different ones of the storage devices 106 of the storage array 105 illustratively exhibit different latencies in processing of IO operations. In some cases, the same storage device may exhibit different latencies for different ones of multiple paths over which that storage device can be accessed from a given one of the host devices 102.

The host devices 102, SAN 104 and storage array 105 in the FIG. 1 embodiment are assumed to be implemented using at least one processing platform each comprising one or more processing devices each having a processor coupled to a memory. Such processing devices can illustratively include particular arrangements of compute, storage and network resources. For example, processing devices in some embodiments are implemented at least in part utilizing virtual resources such as virtual machines (VMs) or Linux containers (LXCs), or combinations of both as in an arrangement in which Docker containers or other types of LXCs are configured to run on VMs.

The host devices 102 and the storage array 105 may be implemented on respective distinct processing platforms, although numerous other arrangements are possible. For example, in some embodiments at least portions of the host devices 102 and the storage array 105 are implemented on the same processing platform. The storage array 105 can therefore be implemented at least in part within at least one processing platform that implements at least a subset of the host devices 102.

The SAN 104 may be implemented using multiple networks of different types to interconnect storage system components. For example, the SAN 104 may comprise a portion of a global computer network such as the Internet, although other types of networks can be part of the SAN 104, including a wide area network (WAN), a local area network (LAN), a satellite network, a telephone or cable network, a cellular network, a wireless network such as a WiFi or WiMAX network, or various portions or combinations of these and other types of networks. The SAN 104 in some embodiments therefore comprises combinations of multiple different types of networks each comprising processing devices configured to communicate using Internet Protocol (IP) or other related communication protocols.

As a more particular example, some embodiments may utilize one or more high-speed local networks in which associated processing devices communicate with one another utilizing Peripheral Component Interconnect express (PCIe) cards of those devices, and networking protocols such as InfiniBand, Gigabit Ethernet or Fibre Channel. Numerous alternative networking arrangements are possible in a given embodiment, as will be appreciated by those skilled in the art.

The host devices 102 comprise respective sets of IO queues 110-1, 110-2, . . . 110-N and respective MPIO drivers 112-1, 112-2, . . . 112-N. The MPIO drivers 112 collectively comprise a multi-path layer of the host devices 102. The multi-path layer provides functionality for receiving and processing fabric performance data from a storage array. Such functionality is provided at least in part using respective instances of path selection logic 114-1, 114-2, . . . 114-N, and respective instances of fabric performance notification logic 116-1, 116-2, . . . 116-N implemented within the MPIO drivers 112.

The MPIO drivers 112 may comprise, for example, otherwise conventional MPIO drivers, such as PowerPath® drivers from Dell Technologies, suitably modified in the manner disclosed herein to provide functionality for receiving and processing fabric performance data from a storage array. Other types of MPIO drivers from other driver vendors may be suitably modified to incorporate functionality for receiving and processing fabric performance data from a storage array as disclosed herein.

The MPIO driver 112-1 is configured to deliver IO operations selected from its corresponding set of IO queues 110-1 to the storage array 105 via selected ones of multiple paths over the SAN 104. The sources of the IO operations stored in the set of IO queues 110-1 illustratively include respective processes of one or more applications executing on the host device 102-1. For example, IO operations can be generated by each of multiple processes of a database application running on the host device 102-1. Such processes issue IO operations for delivery to the storage array 105 over the SAN 104. Other types of sources of IO operations may be present in a given implementation of system 100.

The paths from the host device 102-1 to the storage array 105 illustratively comprise paths associated with respective initiator-target pairs, with each initiator comprising a host bus adaptor (HBA) or other initiating entity of the host device 102-1 and each target comprising a port or other targeted entity corresponding to one or more of the storage devices 106 of the storage array 105. As noted above, the storage devices 106 illustratively comprise LUNs or other types of logical storage devices.

In some embodiments, the paths are associated with respective communication links between the host device 102-1 and the storage array 105 with each such communication link having a negotiated link speed. For example, in conjunction with registration of a given HBA to a switch of the SAN 104, the HBA and the switch may negotiate a link speed. The actual link speed that can be achieved in practice in some cases is less than the negotiated link speed, which is a theoretical maximum value.

Various scheduling algorithms, load balancing algorithms and/or other types of algorithms can be utilized by the WIPIO driver 112-1 in delivering IO operations from the IO queues 110-1 to the storage array 105 over particular paths via the SAN 104. Each such IO operation is assumed to comprise one or more commands for instructing the storage array 105 to perform particular types of storage-related functions such as reading data from or writing data to particular logical volumes of the storage array 105, or other types of functions, such as log sense commands to send requests to the storage array 105 for data corresponding to performance of one or more switch fabrics in the SAN 104. Such commands are assumed to have various payload sizes associated therewith, and the payload associated with a given command is referred to herein as its “command payload.”

A command directed by the host device 102-1 to the storage array 105 is considered an “outstanding” command until such time as its execution is completed in the viewpoint of the host device 102-1, at which time it is considered a “completed” command. The commands illustratively comprise respective SCSI commands, although other command formats can be used in other embodiments. A given such command is illustratively defined by a corresponding command descriptor block (CDB) or similar format construct. The given command can have multiple blocks of payload associated therewith, such as a particular number of 512-byte SCSI blocks or other types of blocks.

In illustrative embodiments to be described below, it is assumed without limitation that the initiators of a plurality of initiator-target pairs comprise respective HBAs of the host device 102-1 and that the targets of the plurality of initiator-target pairs comprise respective ports of the storage array 105. Examples of such HBAs and storage array ports are illustrated in conjunction with the embodiment of FIG. 3 .

Selecting a particular one of multiple available paths for delivery of a selected one of the IO operations of the set of IO queues 110-1 is more generally referred to herein as “path selection.” Path selection as that term is broadly used herein can in some cases involve both selection of a particular 10 operation and selection of one of multiple possible paths for accessing a corresponding logical device of the storage array 105. The corresponding logical device illustratively comprises a LUN or other logical storage volume to which the particular 10 operation is directed.

It should be noted that paths may be added or deleted between the host devices 102 and the storage array 105 in the system 100. For example, the addition of one or more new paths from host device 102-1 to the storage array 105 or the deletion of one or more existing paths from the host device 102-1 to the storage array 105 may result from respective addition or deletion of at least a portion of the storage devices 106 of the storage array 105.

Addition or deletion of paths can also occur as a result of zoning and masking changes or other types of storage system reconfigurations performed by a storage administrator or other user. Some embodiments are configured to send a predetermined command from the host device 102-1 to the storage array 105, illustratively utilizing the MPIO driver 112-1, to determine if zoning and masking information has been changed. The predetermined command can comprise, for example, log select and log sense commands as described herein, a mode sense command, a “vendor unique command” or VU command, or combinations of multiple instances of these or other commands, in an otherwise standardized command format.

In some embodiments, paths are added or deleted in conjunction with addition of a new storage array or deletion of an existing storage array from a storage system that includes multiple storage arrays, possibly in conjunction with configuration of the storage system for at least one of a migration operation and a replication operation.

For example, a storage system may include first and second storage arrays, with data being migrated from the first storage array to the second storage array prior to removing the first storage array from the storage system.

As another example, a storage system may include a production storage array and a recovery storage array, with data being replicated from the production storage array to the recovery storage array so as to be available for data recovery in the event of a failure involving the production storage array.

In these and other situations, path discovery scans may be repeated as needed in order to discover the addition of new paths or the deletion of existing paths.

A given path discovery scan can be performed utilizing known functionality of conventional MPIO drivers, such as PowerPath® drivers.

The path discovery scan in some embodiments may be further configured to identify one or more new LUNs or other logical storage volumes associated with the one or more new paths identified in the path discovery scan. The path discovery scan may comprise, for example, one or more bus scans which are configured to discover the appearance of any new LUNs that have been added to the storage array 105 as well to discover the disappearance of any existing LUNs that have been deleted from the storage array 105.

The MPIO driver 112-1 in some embodiments comprises a user-space portion and a kernel-space portion. The kernel-space portion of the MPIO driver 112-1 may be configured to detect one or more path changes of the type mentioned above, and to instruct the user-space portion of the MPIO driver 112-1 to run a path discovery scan responsive to the detected path changes. Other divisions of functionality between the user-space portion and the kernel-space portion of the MPIO driver 112-1 are possible.

For each of one or more new paths identified in the path discovery scan, the host device 102-1 may be configured to execute a host registration operation for that path. The host registration operation for a given new path illustratively provides notification to the storage array 105 that the host device 102-1 has discovered the new path.

As is apparent from the foregoing, MPIO driver 112-1 of host device 102-1 is configured to control delivery of IO operations from the host device 102-1 to the storage array 105 over selected paths through the SAN 104.

The MPIO driver 112-1 is further configured with fabric performance notification logic 116-1 to send requests to the storage array 105 for data corresponding to performance of one or more switch fabrics in the SAN 104. The fabric performance notification logic 116-1 receives the data corresponding to the performance of the one or more switch fabrics from the storage array 105 and identifies one or more performance issues associated with selected ones of a plurality of paths through the SAN 104 based on the received data. The fabric performance notification logic 116-1 manages IO operations over the selected ones of the plurality of paths responsive to the identified one or more performance issues. The storage array 105 using, for example, a storage controller 120 and fabric performance notification logic 122, receives notifications from the one or more switch fabrics comprising the data corresponding to the performance of the one or more switch fabrics, and stores the performance data in, for example, a log page. The notifications comprise, for example, fabric performance impact notifications (FPINs). The MPIO driver 112-1 comprising the fabric performance notification logic 116-1 is configured to access the stored data utilizing one or more SCSI commands. Additional examples of receiving and processing fabric performance data from a storage array are described below in conjunction with the embodiments of FIGS. 1 through 5 .

In the FIG. 1 embodiment, the storage array 105 comprises a plurality of storage controllers 120 and one or more instances of fabric performance notification logic 122. A more detailed example of the fabric performance notification logic 122 will be described below in conjunction with the embodiments of FIGS. 1 through 5 .

Additional components not explicitly shown in the figure, such as one or more storage caches, may also be provided in the storage array 105 for use in processing 10 operations. For example, in some embodiments, each of the storage controllers 120 has a different local cache or a different allocated portion of a global cache associated therewith, although numerous alternative arrangements are possible. The storage controllers 120 can be implemented as respective storage processors, directors or other storage system components configured to control storage system operations relating to processing of IO operations.

As used herein, a “switch fabric” refers to a network topology comprising nodes interconnected via one or more network switches. Network traffic is spread across a plurality of physical links in a switch fabric. A Fibre Channel is a non-limiting example of a switch fabric topology.

Fibre channels can provide a way for nodes in a switch fabric to understand switch fabric conditions using notifications about switch fabric performance. A non-limiting example of such a notification is an FPIN. However, in order to consume these notifications about fabric performance, a host device needs to be running an operating system and utilizing HBA drivers that are configured to pass the notification to the operating system. However, not all host devices are equipped to support fabric performance notifications. For example, even if a SAN switch fabric and storage arrays support fabric notifications (e.g., FPINs), a host device may be utilizing an operating system and HBAs that do not support the fabric notifications. Accordingly, absent use of techniques disclosed herein, such host devices are not able to take advantage of notifications to handle fabric congestion.

In illustrative embodiments, techniques are provided to enable host devices 102 to take advantage of fabric notifications (e.g., FPINs), even when a host device 102-1 lacks an operating system and HBA drivers that support fabric notifications. For example, in one or more embodiments, a storage array 105 registers for notifications (e.g., FPINs) about link integrity events. When the registered storage array 105 receives a notification, the storage array 105 identifies affected initiators and target ports from a link integrity descriptor in the notification, and updates the details of affected initiator and target ports in a vendor-specific SCSI log page. The log page can capture all details which notification descriptors (e.g., FPIN descriptors) provide such as, but not necessarily limited to, event count, affected initiators and affected target ports. Using regular intervals (e.g., every second, every 10 seconds, every 30 seconds, every minute, etc.) an MPIO driver 112-1, and more specifically, the fabric performance notification logic 116-1 installed on the host device 102-1 utilizes SCSI commands (e.g., log sense commands) to check log pages for any valid notification applicable to any of the initiators of the host device 102-1. The MPIO driver 112-1 can detect link integrity issues with one or more of the initiators or zoned targets, and evaluate event counts for events corresponding to the affected initiators and/or targets. If event count values exceed particular thresholds, the MPIO driver 112-1 sets the affected paths to standby and uses other available paths. Alternatively, the MPIO driver 112-1, and more specifically, the fabric performance notification logic 116-1 throttles IO operations through the affected paths.

For example, referring to FIG. 4 , in the algorithm 400 according to an embodiment, a storage array 105 waits for FPIN notifications from a switch fabric (block 402), receives a fabric performance notification (block 404) and identifies initiators and/or target ports described in the notification (block 406). The initiators and the target ports are affected by an issue with the switch fabric and corresponding IO paths. The initiators and the target ports may be identified with, for example, one or more of world-wide names (WWNs), world-wide port names (WWPNs), world-wide node names (WWNNs), location codes, physical HBA serial numbers, logical partitions (LPARs) and VM identifiers and/or names, and corresponding virtual 10 server Internet Protocol (IP) addresses and/or names. Using the fabric performance and notification logic 122, the storage array 105 stores the FPIN notification and the data included in the FPIN in a data structure such as, for example, a log page (block 408), and waits for polling from a connected host device 102-1 requesting the notification details (block 410). According to the embodiment described in connection with FIG. 4 , upon receipt of the request from the host device 102-1, the fabric performance and notification logic 122 determines whether the requesting host device 102-1 corresponds to a path, initiator and/or target port that is affected by the fabric performance issue that is the subject of the notification. For example, the fabric performance and notification logic 122 analyzes the identified paths, initiators and/or target ports in the notification and, in conjunction with storage controller 120, determines whether the host device 102-1 sent IO operations through the identified paths, initiators and/or target ports. Referring to blocks 412 and 413, if the requesting host device 102-1 does not match the identified paths, initiators and/or target ports in the received notification, the storage array 105 replies to the host device 102-1 that no notification is available. Referring to blocks 412 and 414, if the requesting host device 102-1 matches the identified paths, initiators and/or target ports in the received notification, the storage array 105 replies to the host device 102-1 with the notification details, including an event count. The “event count” refers to a count of problematic events (e.g., link integrity events) affecting IO operations over one or more paths. For example, a link integrity event refers to a situation where at least a part of an IO operation path fails causing the IO operation to fail. The event count may be in terms of a number of events over a period of time (e.g., number of events every ten seconds, every 30 seconds, every minute, etc.).

Referring to FIG. 5 , in the algorithm 500 according to an embodiment, a host device 102-1 regularly polls a storage array 105 with requests for fabric performance information (block 502). For example, the host device 102-1, and more particularly, the fabric performance notification logic 116-1 regularly sends requests (e.g., in the form an SCSI command) for data corresponding to performance of one or more switch fabrics in the SAN 104. The storage array 105 replies to the host device 102-1 with the data and, referring to block 504, the host device 102-1 identifies one or more performance issues associated with one or more paths through which the host device 102-1 sent or is sending IO operations. In an embodiment, referring to block 506, when the event count is reported to the host device 102-1, the MPIO driver 112-1 determines whether the event count exceeds a given threshold. For example, the threshold can be set so that if there are multiple events in a relatively short period of time indicating a relatively serious issue, the MPIO driver 112-1, and more particularly, the path selection logic 114-1 will manage the IO operations by, for example, throttling the IO operations over paths having performance issues and/or sending the IO operations over paths unaffected by performance issues. Alternatively, if there are few events over a period of time indicating little or no issues with IO transmission, the MPIO driver 112-1 may conclude that IO operations do not require remedial actions. The threshold can be programmed by a user or automatically determined by the MPIO driver 112-1.

Referring to block 508, assuming the event count threshold is met, the path selection logic 114-1 in combination with the fabric performance notification logic 116-1 determines whether the performance issue(s) are on all or some IO operation paths. At block 510, if the performance issue(s) are on all IO operation paths, the MPIO driver 112-1 temporarily throttles IO operations on all the paths. At block 512, if the performance issue(s) are on some IO operation paths, the MPIO driver 112-1 temporarily throttles IO operations on some of the paths and/or sends new IO operations on the paths unaffected by performance issues.

As noted herein, information can be obtained by the host device 102-1 from the storage array 105, or information can be obtained by the storage array 105 from the host device 102-1 utilizing an in-band communication mechanism in which one or more predetermined commands in a designated storage protocol are sent from the host device 102-1 to the storage array 105 or vice versa. Such predetermined commands can comprise, for example, log sense and log select commands, a mode sense command, a VU command, or combinations of multiple instances of these or other commands, in an otherwise standardized command format, such as a SCSI format or other type of format.

Additionally or alternatively, information can be obtained by the host device 102-1 from the storage array 105, or information can be obtained by the storage array 105 from the host device 102-1 utilizing an out-of-band communication mechanism. For example, an out-of-band communication mechanism of this type can involve host management software of the host device 102-1 communicating with storage array management software of the storage array 105 over an IP network connection or other type of network connection.

These and other functions related to receiving and processing fabric performance data from a storage array that are referred to herein as being performed by or under the control of the MPIO driver 112-1 can in some embodiments be performed at least in part outside of the MPIO driver 112-1, such as in the host device 102-1 generally.

References herein to an MPIO driver such as MPIO driver 112-1 being configured to receive and process fabric performance data from a storage array are intended to be broadly construed, and should not be viewed as being limited to any particular storage arrangement, such as storage in a particular host device component or using a particular format. Accordingly, such storage can be in a memory or other storage device that is outside of the MPIO driver.

Hosts available in a data center have diverse configurations, and all hosts are not able to take advantage of fabric notification (e.g., FPIN) enhancements. Absent use of the techniques for receiving and processing fabric performance data from a storage array as disclosed herein, legacy host devices utilizing operating systems, drivers and/or HBAs that do not support particular fabric notification techniques are not able to take advantage of the fabric notification techniques and not able to effectively handle fabric congestion.

Such drawbacks are advantageously overcome in illustrative embodiments herein by utilization of a multi-path layer comprising one or more of the MPIO drivers 112 to receive and process fabric performance data from a storage array as described above. These embodiments therefore provide a significant advance over conventional configurations that are not equipped to receive fabric performance notifications from a fabric or from a storage array. For example, host devices in illustrative embodiments are advantageously configured to receive fabric performance details from a storage array, so that the host devices can identify performance issues in paths used for IO operations, and the MPIO drivers 112 can take remedial actions by, for example, throttling IO operations over affected paths and/or rerouting IO operations to paths without performance issues, leading to enhanced overall performance.

The above-described functions associated with receiving and processing fabric performance data from a storage array in the MPIO driver 112-1 are carried out at least in part under the control of its path selection logic 114-1 and/or fabric performance notification logic 116-1. For example, the path selection logic 114-1 and/or fabric performance notification logic 116-1 are illustratively configured to control performance of an algorithm comprising the steps of the flow diagram to be described below in conjunction with FIG. 2 and/or the algorithms comprising the steps of in the flow diagrams of FIGS. 4 and 5 . In other embodiments, one or more such steps can be more generally performed by the host device 102-1.

It is assumed that each of the other MPIO drivers 112 is configured in a manner similar to that described above and elsewhere herein for the first MPIO driver 112-1. The other host devices 102 of the system 100 are therefore also configured to communicate over the SAN 104 with the storage array 105. The MPIO drivers 112 of such other host devices are each similarly configured to deliver IO operations from its corresponding one of the sets of IO queues 110 to the storage array 105 over selected paths through the SAN 104, and to perform the disclosed functionality for receiving and processing fabric performance data from a storage array.

Accordingly, functionality described above in the context of the first MPIO driver 112-1 and the first host device 102-1 is assumed to be similarly performed by each of the other MPIO drivers 112-2 through 112-N and/or more generally by their respective host devices 102-2 through 102-N.

The MPIO drivers 112 may be otherwise configured utilizing well-known MPIO functionality such as that described in “Dell EMC SC Series Storage and Microsoft Multipath I/O,” Dell EMC, CML 1004, July 2018, which is incorporated by reference herein. Such conventional MPIO functionality is suitably modified in illustrative embodiments disclosed herein to support receiving and processing fabric performance data from a storage array.

Although in some embodiments certain commands used by the host devices 102 to communicate with the storage array 105 illustratively comprise SCSI commands, other types of commands and command formats can be used in other embodiments. For example, some embodiments can implement 10 operations utilizing command features and functionality associated with NVM Express (NVMe), as described in the NVMe Specification, Revision 1.3, May 2017, which is incorporated by reference herein. Other storage protocols of this type that may be utilized in illustrative embodiments disclosed herein include NVMe over Fabric, also referred to as NVMeoF.

The storage array 105 in the present embodiment is assumed to comprise a persistent memory that is implemented using a flash memory or other type of non-volatile memory of the storage array 105. More particular examples include NAND-based flash memory or other types of non-volatile memory such as resistive RAM, phase change memory, spin torque transfer magneto-resistive RAM (STT-MRAM) and Intel Optane™ devices based on 3D XPoint™ memory. The persistent memory is further assumed to be separate from the storage devices 106 of the storage array 105, although in other embodiments the persistent memory may be implemented as a designated portion or portions of one or more of the storage devices 106. For example, in some embodiments the storage devices 106 may comprise flash-based storage devices, as in embodiments involving all-flash storage arrays, or may be implemented in whole or in part using other types of non-volatile memory.

As mentioned above, communications between the host devices 102 and the storage array 105 may utilize PCIe connections or other types of connections implemented over one or more networks. For example, illustrative embodiments can use interfaces such as Internet SCSI (iSCSI), Serial Attached SCSI (SAS) and Serial ATA (SATA). Numerous other interfaces and associated communication protocols can be used in other embodiments.

The storage array 105 in some embodiments may be implemented as part of cloud infrastructure in the form of a cloud-based system such as an Amazon Web Services (AWS) system. Other examples of cloud-based systems that can be used to provide at least portions of the storage array 105 and possibly other portions of system 100 include Google Cloud Platform (GCP) and Microsoft Azure.

The storage devices 106 of the storage arrays 105 can be implemented using solid state drives (SSDs). Such SSDs are implemented using non-volatile memory (NVM) devices such as flash memory. Other types of NVM devices that can be used to implement at least a portion of the storage devices 106 include non-volatile random access memory (NVRAM), phase-change RAM (PC-RAM) and magnetic RAM (MRAM). These and various combinations of multiple different types of NVM devices or other storage devices may also be used. For example, hard disk drives (HDDs) can be used in combination with or in place of SSDs or other types of NVM devices. Accordingly, numerous other types of electronic or magnetic media can be used in implementing at least a subset of the storage devices 106.

The storage array 105 may additionally or alternatively be configured to implement multiple distinct storage tiers of a multi-tier storage system. By way of example, a given multi-tier storage system may comprise a fast tier or performance tier implemented using flash storage devices or other types of SSDs, and a capacity tier implemented using HDDs, possibly with one or more such tiers being server based. A wide variety of other types of storage devices and multi-tier storage systems can be used in other embodiments, as will be apparent to those skilled in the art. The particular storage devices used in a given storage tier may be varied depending on the particular needs of a given embodiment, and multiple distinct storage device types may be used within a single storage tier. As indicated previously, the term “storage device” as used herein is intended to be broadly construed, and so may encompass, for example, SSDs, HDDs, flash drives, hybrid drives or other types of storage products and devices, or portions thereof, and illustratively include logical storage devices such as LUNs.

As another example, the storage array 105 may be used to implement one or more storage nodes in a cluster storage system comprising a plurality of storage nodes interconnected by one or more networks.

It should therefore be apparent that the term “storage array” as used herein is intended to be broadly construed, and may encompass multiple distinct instances of a commercially-available storage array. For example, the storage array 105 may comprise one or more storage arrays such as one or more VNX®, VMAX®, Unity™ or PowerMax™ storage arrays, commercially available from Dell Technologies.

Other types of storage products that can be used in implementing a given storage system in illustrative embodiments include software-defined storage, cloud storage, object-based storage and scale-out storage. Combinations of multiple ones of these and other storage types can also be used in implementing a given storage system in an illustrative embodiment.

In some embodiments, a storage system comprises first and second storage arrays arranged in an active-active configuration. For example, such an arrangement can be used to ensure that data stored in one of the storage arrays is replicated to the other one of the storage arrays utilizing a synchronous replication process. Such data replication across the multiple storage arrays can be used to facilitate failure recovery in the system 100. One of the storage arrays may therefore operate as a production storage array relative to the other storage array which operates as a backup or recovery storage array.

It is to be appreciated, however, that embodiments disclosed herein are not limited to active-active configurations or any other particular storage system arrangements. Accordingly, illustrative embodiments herein can be configured using a wide variety of other arrangements, including, by way of example, active-passive arrangements, active-active Asymmetric Logical Unit Access (ALUA) arrangements, and other types of ALUA arrangements.

These and other storage systems can be part of what is more generally referred to herein as a processing platform comprising one or more processing devices each comprising a processor coupled to a memory. A given such processing device may correspond to one or more virtual machines or other types of virtualization infrastructure such as Docker containers or other types of LXCs. As indicated above, communications between such elements of system 100 may take place over one or more networks.

The term “processing platform” as used herein is intended to be broadly construed so as to encompass, by way of illustration and without limitation, multiple sets of processing devices and one or more associated storage systems that are configured to communicate over one or more networks. For example, distributed implementations of the host devices 102 are possible, in which certain ones of the host devices 102 reside in one data center in a first geographic location while other ones of the host devices 102 reside in one or more other data centers in one or more other geographic locations that are potentially remote from the first geographic location. Thus, it is possible in some implementations of the system 100 for different ones of the host devices 102 to reside in different data centers than the storage array 105.

Numerous other distributed implementations of the host devices 102 and/or the storage array 105 are possible. Accordingly, the storage array 105 can also be implemented in a distributed manner across multiple data centers.

It is to be appreciated that these and other features of illustrative embodiments are presented by way of example only, and should not be construed as limiting in any way. Accordingly, different numbers, types and arrangements of system components such as host devices 102, SAN 104, storage array 105, storage devices 106, sets of IO queues 110, MPIO drivers 112 and instances of path selection logic 114 and fabric performance notification logic 116 can be used in other embodiments.

It should also be understood that the particular sets of modules and other components implemented in the system 100 as illustrated in FIG. 1 are presented by way of example only. In other embodiments, only subsets of these components, or additional or alternative sets of components, may be used, and such components may exhibit alternative functionality and configurations.

The operation of the information processing system 100 will now be described in further detail with reference to the flow diagram of the illustrative embodiment of FIG. 2 . The process as shown includes steps 200 through 206, and is suitable for use in the system 100 but is more generally applicable to other types of systems comprising at least one host device and a storage system. The storage system in this embodiment is assumed to comprise at least one storage array having a plurality of storage devices. The storage devices can include logical storage devices such as LUNs or other logical storage volumes.

The steps of the FIG. 2 process are illustratively performed at least in part by or under the control of an MPIO driver of a given host device. For example, portions of the process may be carried out under the control of software, firmware and/or hardware of an instance of path selection logic deployed within the MPIO driver. Accordingly, the FIG. 2 process may be viewed as an example of an algorithm performed by the path selection logic 114-1 and/or fabric performance notification logic 116-1 of the MPIO driver 112-1 of host device 102-1. Other arrangements of host device components and/or other system components can be configured to perform at least portions of one or more of the steps in other embodiments.

In step 200, the MPIO driver sends one or more requests to a storage system for data corresponding to performance of one or more switch fabrics in a network. The one or more requests for the data corresponding to the performance of the one or more switch fabrics are transmitted to the storage system utilizing one or more SCSI commands such as, for example, a log sense command.

In step 202, the MPIO driver receives the data corresponding to the performance of the one or more switch fabrics in the network from the storage system. The data comprises, for example, identification information of at least one of one or more initiators and one or more targets associated with the one or more switch fabrics.

In step 204, the MPIO driver identifies one or more performance issues associated with at least one of selected ones of a plurality of paths through the network based on the received data. In identifying the one or more performance issues, the MPIO driver is configured to determine that at least one of the one or more initiators and the one or more targets correspond to the at least one of the selected ones of the plurality of paths.

In step 206, the MPIO driver manages one or more IO operations over the at least one of the selected ones of the plurality of paths responsive to the identified one or more performance issues. In managing the one or more of the IO operations, the MPIO driver throttles given ones of the IO operations over the at least one of the selected ones of the plurality of paths and/or sends given ones of the IO operations over one or more paths of the plurality of paths unaffected by the identified one or more performance issues.

The data corresponding to the performance of the one or more switch fabrics in the network comprises, for example, a count of events affecting IO operations over the at least one of the selected ones of the plurality of paths. In one or more embodiments, the MPIO driver determines whether the count exceeds a threshold, and executes the management of the one or more of the IO operations responsive to the count exceeding the threshold.

In one or more embodiments, the storage system receives a notification from the one or more switch fabrics comprising the data corresponding to the performance of the one or more switch fabrics. The notification may comprise an FPIN. The notification comprises, for example, a confluence of information related the affected switch fabric and paths from affected host devices to storage arrays, including affected initiators and target ports.

According to an embodiment, the performance issues comprise lost credit, credit stall and/or oversubscription. Fabric congestion is caused by, for example: (i) lost credit, which occurs when links between, for example, host devices and storage arrays, experience errors; (ii) credit stall, which occurs when frame processing stops or slows down; and (iii) oversubscription, which occurs when received IO operations are more than an end device is able to handle.

The embodiments can be applied to multiple types of fabric performance notifications (e.g., FPINs). For example, target ports may be registered for peer congestion fabric performance notifications. When an initiator connected port in a switch fabric is affected due to congestion, for example, in the case of an oversubscription issue, a target port, on receiving a peer congestion notification, informs a host device about the peer congestion issue. In response, the host MPIO driver (e.g., MPIO driver 112-1) may throttle IO operations via paths through an affected initiator or use alternate paths without affected initiators.

In another example, target ports may be registered for congestion fabric performance notifications. When a target connected port in a switch fabric is affected due to congestion, a target port, on receiving a congestion notification, informs a host about the congestion issue. In response, the host MPIO driver (e.g., MPIO driver 112-1) may throttle IO operations via paths that are connected to the affected target port.

Multiple additional instances of the FIG. 2 process may be performed in respective additional host devices that share the storage array. Other embodiments can include multiple storage arrays, with the disclosed functionality for receiving and processing fabric performance data from a storage array being implemented for each of those storage arrays.

The particular processing operations and other system functionality described in conjunction with the flow diagram of FIG. 2 are presented by way of illustrative example only, and should not be construed as limiting the scope of the disclosure in any way. Alternative embodiments can use other types of processing operations involving host devices, storage systems and functionality for receiving and processing fabric performance data from a storage array. For example, the ordering of the process steps may be varied in other embodiments, or certain steps may be performed at least in part concurrently with one another rather than serially. Also, one or more of the process steps may be repeated periodically, or multiple instances of the process can be performed in parallel with one another in order to implement the disclosed functionality for receiving and processing fabric performance data from a storage array within a given information processing system.

Functionality such as that described in conjunction with the flow diagram of FIG. 2 can be implemented at least in part in the form of one or more software programs stored in memory and executed by a processor of a processing device such as a computer or server. As will be described below, a memory or other storage device having executable program code of one or more software programs embodied therein is an example of what is more generally referred to herein as a “processor-readable storage medium.”

Referring now to FIG. 3 , another illustrative embodiment is shown. In this embodiment, an information processing system 300 comprises one or more instances of path selection logic 314 and fabric performance notification logic 316 and 321. The system 300 is configured in accordance with a layered system architecture that illustratively includes a host device processor layer 330, an MPIO layer 332, an HBA layer 334, a switch fabric layer 336, a storage array port layer 338 and a storage array processor layer 340. The host device processor layer 330, the MPIO layer 332 and the HBA layer 334 are associated with one or more host devices, the switch fabric layer 336 is associated with one or more SANs or other types of networks, and the storage array port layer 338 and storage array processor layer 340 are associated with one or more storage arrays (“SAs”).

The system 300 in this embodiment implements receiving and processing fabric performance data from a storage array as characterized by fabric performance notification logic 316. The fabric performance notification logic 316 is illustratively shown as part of the MPIO layer 332. Alternatively, the fabric performance notification logic 316 in other embodiments is illustratively stored, at least partially, in the host device processor layer 330. It is also possible in some embodiments that the fabric performance notification logic 316 can be incorporated within a data structure of the path selection logic 314. The fabric performance notification logic 316 (or 116) illustratively sends requests to a storage array for data corresponding to performance of one or more switch fabrics SF1 and SF2. The fabric performance notification logic 316 receives the data corresponding to the performance of the one or more switch fabrics SF1 and SF2 from the storage array and identifies one or more performance issues associated with selected ones of a plurality of paths through the switch fabrics SF1 and SF2 based on the received data. The fabric performance notification logic 316, along with the path selection logic 314 manages IO operations over the selected ones of the plurality of paths responsive to the identified one or more performance issues.

According to an embodiment, a storage array waits for and receives fabric performance notifications from a switch fabric SF1 and/or SF2 and identifies initiator(s) HBA1 and/or HBA2 and target port(s) PORT1 and/or PORT2 described in the notification. The initiator(s) HBA1 and/or HBA2 and the target port(s) PORT1 and/or PORT2 are affected by an issue with the switch fabric SF1 and/or SF2 and corresponding IO paths. Using the fabric performance and notification logic 321 (or 122), the storage array stores the fabric performance notifications and the data included in the fabric performance notifications in a data structure such as, for example, a log page, and waits for polling from a connected host device requesting the notification details.

The MPIO layer 332 is an example of what is also referred to herein as a multi-path layer, and comprises one or more MPIO drivers implemented in respective host devices. Each such MPIO driver illustratively comprises an instance of path selection logic 314 and fabric performance notification logic 316 configured to implement functionality for receiving and processing fabric performance data from a storage array substantially as previously described. Additional or alternative layers and path selection and/or fabric performance notification logic arrangements can be used in other embodiments.

The fabric performance notification logic 321 implemented in the storage array processor layer 340 receives fabric performance notifications from the switch fabrics SF1 and SF2, and stores the data from the notifications in a data structure accessible to the host device via, for example, one or more SCSI commands. For example, the fabric performance notification logic 321 can include functionality for the system 300 the same or similar to that described in connection with the fabric performance notification logic 122. For example, upon receipt of a request from a host device, the fabric performance and notification logic 321 determines whether the requesting host device corresponds to a path, initiator (e.g., HBA1 and/or HBA2) and/or target port (e.g. PORT1 and/or PORT2) that is affected by the fabric performance issue that is the subject of the notification. For example, the fabric performance and notification logic 321 analyzes the identified paths, initiators and/or target ports in the notification and determines whether a host device sent IO operations through the identified paths, initiators and/or target ports. It is also possible in some embodiments that the fabric performance notification logic 321 can include multiple logic instances for respective ones of a plurality of storage arrays of the system 300.

In the system 300, path selection logic 314 is configured to select different paths for sending IO operations and/or commands from a given host device to a storage array. These paths as illustrated in the figure include a first path from a particular HBA denoted HBA1 through a particular switch fabric denoted SF1 to a particular storage array port denoted PORT1, and a second path from another particular HBA denoted HBA2 through another particular switch fabric denoted SF2 to another particular storage array port denoted PORT2.

These two particular paths are shown by way of illustrative example only, and in many practical implementations there will typically be a much larger number of paths between the one or more host devices and the one or more storage arrays, depending upon the specific system configuration and its deployed numbers of HBAs, switch fabrics and storage array ports. For example, each host device in the FIG. 3 embodiment can illustratively have a set of n paths to a shared storage array, or alternatively different ones of the host devices can have different numbers and types of paths to the storage array.

The path selection logic 314 of the MPIO layer 332 in this embodiment therefore selects paths for delivery of IO operations and/or commands to the one or more storage arrays having the storage array ports of the storage array port layer 338. In selecting the paths, the path selection logic 314 illustratively limits amounts of IO operations and/or commands that are delivered over one or more paths to particular ones of the ports of a storage array.

It is assumed in this embodiment that the host devices through their respective MPIO drivers and respective instances of path selection logic 314 and fabric performance notification logic 316 provide functionality for receiving and processing fabric performance data from a storage array, possibly with involvement of other host device components.

Accordingly, in some embodiments, the path selection logic 314 utilizes the fabric performance notification logic 316 in determining appropriate paths over which to send particular IO operations and/or commands to ports of one or more storage arrays. As described elsewhere herein, such receiving and processing of fabric performance data can substantially improve system performance.

Some implementations of the system 300 can include a relatively large number of host devices (e.g., 1000 or more host devices), although as indicated previously different numbers of host devices, and possibly only a single host device, may be present in other embodiments. Each of the host devices is typically allocated with a sufficient number of HBAs to accommodate predicted performance needs. In some cases, the number of HBAs per host device is on the order of 4, 8 or 16 HBAs, although other numbers of HBAs could be allocated to each host device depending upon the predicted performance needs. A typical storage array may include on the order of 128 ports, although again other numbers can be used based on the particular needs of the implementation. The number of host devices per storage array port in some cases can be on the order of 10 host devices per port. The HBAs of the host devices are assumed to be zoned and masked to the storage array ports in accordance with the predicted performance needs, including user load predictions.

A given host device of system 300 can be configured to initiate an automated path discovery process to discover new paths responsive to updated zoning and masking or other types of storage system reconfigurations performed by a storage administrator or other user. For certain types of host devices, such as host devices using particular operating systems such as Windows, ESX or Linux, automated path discovery via the MPIO drivers of a multi-path layer is typically supported. Other types of host devices using other operating systems such as AIX in some implementations do not necessarily support such automated path discovery, in which case alternative techniques can be used to discover paths.

The particular features and functionality of the illustrative embodiments described above can be varied in other embodiments.

Also, as mentioned previously, different instances of the above-described algorithms and other fabric performance data receiving and processing techniques can be performed by different MPIO drivers in different host devices.

The particular fabric performance data receiving and processing arrangements described above are therefore presented by way of illustrative example only. Numerous alternative arrangements of these and other features can be used in implementing the fabric performance data receiving and processing functionality in other illustrative embodiments.

The illustrative embodiments disclosed herein can provide a number of significant advantages relative to conventional arrangements that fail to provide host device multi-pathing software with sufficient information about switch fabric congestion. Advantageously, the embodiments configure a multi-path layer of one or more host devices to include functionality for receiving and processing fabric performance data from a storage array, leading to enhanced overall performance. These embodiments provide a significant advance over conventional techniques, which do not enable certain host devices to take advantage of fabric performance notifications. For example, illustrative embodiments are advantageously configured to enable hosts to take advantage of fabric performance notifications, even when the host lacks an operating system and HBA drivers that support fabric performance notifications. In one or more embodiments, a storage array registers for notifications about link integrity events, and stores details of affected initiators and target ports in its vendor-specific SCSI log page. Advantageously, MPIO drivers installed on hosts utilize log sense commands to check the log page for any valid notification applicable to any of the host initiators.

The embodiments enable MPIO drivers of host devices that may lack software and/or firmware for receiving performance notifications from a switch fabric to use a storage array to detect link integrity issues with one or more initiators or zoned targets, and evaluate event counts for events corresponding to the affected initiators and/or targets. The embodiments advantageously provide fabric performance notifications to host devices through a storage array acting as an intermediary for the information.

It is to be appreciated that the particular advantages described above are associated with particular illustrative embodiments and need not be present in other embodiments. Also, the particular types of information processing system features and functionality as illustrated in the drawings and described above are exemplary only, and numerous other arrangements may be used in other embodiments.

It was noted above that portions of an information processing system as disclosed herein may be implemented using one or more processing platforms. Illustrative embodiments of such platforms will now be described in greater detail. These and other processing platforms may be used to implement at least portions of other information processing systems in other embodiments. A given such processing platform comprises at least one processing device comprising a processor coupled to a memory.

One illustrative embodiment of a processing platform that may be used to implement at least a portion of an information processing system comprises cloud infrastructure including virtual machines implemented using a hypervisor that runs on physical infrastructure. The cloud infrastructure further comprises sets of applications running on respective ones of the virtual machines under the control of the hypervisor. It is also possible to use multiple hypervisors each providing a set of virtual machines using at least one underlying physical machine. Different sets of virtual machines provided by one or more hypervisors may be utilized in configuring multiple instances of various components of the system.

These and other types of cloud infrastructure can be used to provide what is also referred to herein as a multi-tenant environment. One or more system components such as virtual machines, or portions thereof, are illustratively implemented for use by tenants of such a multi-tenant environment.

Cloud infrastructure as disclosed herein can include cloud-based systems such as Amazon Web Services, Google Cloud Platform and Microsoft Azure. Virtual machines provided in such systems can be used to implement a fast tier or other front-end tier of a multi-tier storage system in illustrative embodiments. A capacity tier or other back-end tier of such a multi-tier storage system can be implemented using one or more object stores such as Amazon S3, Google Cloud Platform Cloud Storage, and Microsoft Azure Blob Storage.

In some embodiments, the cloud infrastructure additionally or alternatively comprises a plurality of containers illustratively implemented using respective operating system kernel control groups of one or more container host devices. For example, a given container of cloud infrastructure illustratively comprises a Docker container or other type of LXC implemented using a kernel control group. The containers may run on virtual machines in a multi-tenant environment, although other arrangements are possible. The containers may be utilized to implement a variety of different types of functionality within the system 100. For example, containers can be used to implement respective compute nodes or storage nodes of a cloud-based system. Again, containers may be used in combination with other virtualization infrastructure such as virtual machines implemented using a hypervisor.

Another illustrative embodiment of a processing platform that may be used to implement at least a portion of an information processing system comprises a plurality of processing devices which communicate with one another over at least one network. The network may comprise any type of network, including by way of example a global computer network such as the Internet, a WAN, a LAN, a satellite network, a telephone or cable network, a cellular network, a wireless network such as a WiFi or WiMAX network, or various portions or combinations of these and other types of networks.

Each processing device of the processing platform comprises a processor coupled to a memory. The processor may comprise a microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a graphics processing unit (GPU) or other type of processing circuitry, as well as portions or combinations of such circuitry elements. The memory may comprise random access memory (RAM), read-only memory (ROM), flash memory or other types of memory, in any combination. The memory and other memories disclosed herein should be viewed as illustrative examples of what are more generally referred to as “processor-readable storage media” storing executable program code of one or more software programs.

Articles of manufacture comprising such processor-readable storage media are considered illustrative embodiments. A given such article of manufacture may comprise, for example, a storage array, a storage disk or an integrated circuit containing RAM, ROM, flash memory or other electronic memory, or any of a wide variety of other types of computer program products. The term “article of manufacture” as used herein should be understood to exclude transitory, propagating signals.

Also included in the processing device is network interface circuitry, which is used to interface the processing device with the network and other system components, and may comprise conventional transceivers.

As another example, portions of a given processing platform in some embodiments can comprise converged infrastructure such as VxRail™, VxRack™, VxRack™ FLEX, VxBlock™ or Vblock® converged infrastructure from Dell Technologies.

Again, these particular processing platforms are presented by way of example only, and other embodiments may include additional or alternative processing platforms, as well as numerous distinct processing platforms in any combination, with each such platform comprising one or more computers, servers, storage devices or other processing devices.

It should therefore be understood that in other embodiments different arrangements of additional or alternative elements may be used. At least a subset of these elements may be collectively implemented on a common processing platform, or each such element may be implemented on a separate processing platform.

Also, numerous other arrangements of computers, servers, storage devices or other components are possible in an information processing system as disclosed herein. Such components can communicate with other elements of the information processing system over any type of network or other communication media.

As indicated previously, components of an information processing system as disclosed herein can be implemented at least in part in the form of one or more software programs stored in memory and executed by a processor of a processing device. For example, at least portions of the functionality of host devices 102, SAN 104 and storage array 105 are illustratively implemented in the form of software running on one or more processing devices. As a more particular example, the instances of path selection logic 114 and fabric performance notification logic 116 and 122 may be implemented at least in part in software, as indicated previously herein.

It should again be emphasized that the above-described embodiments are presented for purposes of illustration only. Many variations and other alternative embodiments may be used. For example, the disclosed techniques are applicable to a wide variety of other types of information processing systems, utilizing other arrangements of host devices, networks, storage systems, storage arrays, storage devices, processors, memories, IO queues, MPIO drivers, path selection logic, fabric performance notification logic and additional or alternative components. Also, the particular configurations of system and device elements and associated processing operations illustratively shown in the drawings can be varied in other embodiments. For example, a wide variety of different MPIO driver configurations and associated fabric performance data receiving and processing arrangements can be used in other embodiments. Moreover, the various assumptions made above in the course of describing the illustrative embodiments should also be viewed as exemplary rather than as requirements or limitations. Numerous other alternative embodiments within the scope of the appended claims will be readily apparent to those skilled in the art. 

What is claimed is:
 1. An apparatus comprising: a host device comprising a processor coupled to a memory; the host device being configured to communicate over a network with a storage system; the host device comprising: a multi-path input-output driver configured to control delivery of input-output operations from the host device to the storage system over selected ones of a plurality of paths through the network; wherein the multi-path input-output driver is further configured: to send one or more requests to the storage system for data corresponding to performance of one or more switch fabrics in the network, wherein the one or more switch fabrics comprise one or more network switches; to receive a first portion of the data corresponding to the performance of the one or more switch fabrics in the network from the storage system, wherein the first portion of the data is from a first switch fabric notification identifying at least one of one or more initiators and one or more targets used in one or more of the input-output operations; to identify one or more performance issues associated with at least one of the selected ones of the plurality of paths based on the first portion of the data; and to manage the one or more of the input-output operations responsive to the identified one or more performance issues; wherein the first portion of the data comprises a count of events where at least part of the at least one of the selected ones of the plurality of paths fails; wherein, in identifying the one or more performance issues, the multi-path input-output driver is configured to determine whether the count of events exceeds a threshold number of events; and wherein the multi-path input-output driver is further configured to receive an indication of unavailability of a second portion of the data corresponding to the performance of the one or more switch fabrics in the network, and wherein the second portion of the data is from a second switch fabric notification failing to identify the one or more initiators and the one or more targets used in the one or more of the input-output operations.
 2. The apparatus of claim 1 wherein the one or more requests for the data corresponding to the performance of the one or more switch fabrics are transmitted to the storage system utilizing one or more Small Computer System Interface (SCSI) commands.
 3. The apparatus of claim 2 wherein the one or more SCSI commands comprise a log sense command.
 4. The apparatus of claim 1 wherein, in managing the one or more of the input-output operations, the multi-path input-output driver is configured to throttle given ones of the input-output operations over the at least one of the selected ones of the plurality of paths.
 5. The apparatus of claim 1 wherein, in managing the one or more of the input-output operations, the multi-path input-output driver is configured to send given ones of the input-output operations over one or more paths of the plurality of paths unaffected by the identified one or more performance issues.
 6. The apparatus of claim 1 wherein, in identifying the one or more performance issues, the multi-path input-output driver is further configured to determine that the at least one of the one or more initiators and the one or more targets used in the one or more of the input-output operations correspond to the at least one of the selected ones of the plurality of paths.
 7. The apparatus of claim 1 wherein the multi-path input-output driver is further configured to execute the management of the one or more of the input-output operations responsive to the count of events exceeding the threshold.
 8. The apparatus of claim 1 wherein the storage system receives the first and second switch fabric notifications from the one or more switch fabrics.
 9. The apparatus of claim 8 wherein the first and second switch fabric notifications each comprise a fabric performance impact notification (FPIN).
 10. The apparatus of claim 8 wherein the storage system stores the data corresponding to the performance of the one or more switch fabrics, and wherein the multi-path input-output driver is configured to access at least a portion of the stored data utilizing one or more Small Computer System Interface (SCSI) commands.
 11. The apparatus of claim 1 wherein the identified one or more performance issues comprise at least one of lost credit, credit stall and oversubscription.
 12. A method performed by a host device configured to communicate over a network with a storage system, comprising: configuring a multi-path input-output driver of the host device to control delivery of input-output operations from the host device over selected ones of a plurality of paths through the network; the multi-path input-output driver: sending one or more requests to the storage system for data corresponding to performance of one or more switch fabrics in the network, wherein the one or more switch fabrics comprise one or more network switches; receiving a first portion of the data corresponding to the performance of the one or more switch fabrics in the network from the storage system, wherein the first portion of the data is from a first switch fabric notification identifying at least one of one or more initiators and one or more targets used in one or more of the input-output operations; identifying one or more performance issues associated with at least one of the selected ones of the plurality of paths based on the first portion of the data; and managing the one or more of the input-output operations responsive to the identified one or more performance issues; wherein the first portion of the data comprises a count of events where at least part of the at least one of the selected ones of the plurality of paths fails; wherein, in identifying the one or more performance issues comprises, the multi-path input-output driver determines whether the count of events exceeds a threshold number of events; wherein the multi-path input-output driver receives an indication of unavailability of a second portion of the data corresponding to the performance of the one or more switch fabrics in the network, and wherein the second portion of the data is from a second switch fabric notification failing to identify the one or more initiators and the one or more targets used in the one or more of the input-output operations; and wherein the host device comprises a processor coupled to a memory.
 13. The method of claim 12 wherein in identifying the one or more performance issues, the multi-path input-output driver further determines that the at least one of the one or more initiators and the one or more targets used in the one or more of the input-output operations correspond to the at least one of the selected ones of the plurality of paths.
 14. The method of claim 12 wherein the multi-path input-output driver executes the managing of the one or more of the input-output operations responsive to the count of events exceeding the threshold.
 15. The method of claim 12 wherein, in managing the one or more of the input-output operations, the multi-path input-output driver throttles given ones of the input-output operations over the at least one of the selected ones of the plurality of paths.
 16. The method of claim 12 wherein, in managing the one or more of the input-output operations, the multi-path input-output driver sends given ones of the input-output operations over one or more paths of the plurality of paths unaffected by the identified one or more performance issues.
 17. The method of claim 12 wherein the storage system receives the first and second switch fabric notifications from the one or more switch fabrics.
 18. A computer program product comprising a non-transitory processor-readable storage medium having stored therein program code of one or more software programs, wherein the program code, when executed by a host device comprising a multi-path input-output driver, the host device being configured to communicate over a network with a storage system, causes the multi-path input-output driver: to control delivery of input-output operations from the host device to the storage system over selected ones of a plurality of paths through the network; to send one or more requests to the storage system for data corresponding to performance of one or more switch fabrics in the network, wherein the one or more switch fabrics comprise one or more network switches; to receive a first portion of the data corresponding to the performance of the one or more switch fabrics in the network from the storage system, wherein the first portion of the data is from a first switch fabric notification identifying at least one of one or more initiators and one or more targets used in one or more of the input-output operations; to identify one or more performance issues associated with at least one of the selected ones of the plurality of paths based on the first portion of the data; and to manage the one or more of the input-output operations responsive to the identified one or more performance issues; wherein the first portion of the data comprises a count of events where at least part of the at least one of the selected ones of the plurality of paths fails; wherein, in identifying the one or more performance issues, the program code causes the multi-path input-output driver to determine whether the count of events exceeds a threshold number of events; and wherein the program code further causes the multi-path input-output driver to receive an indication of unavailability of a second portion of the data corresponding to the performance of the one or more switch fabrics in the network, and wherein the second portion of the data is from a second switch fabric notification failing to identify the one or more initiators and the one or more targets used in the one or more of the input-output operations.
 19. The computer program product of claim 18 wherein in identifying the one or more performance issues, the program code further causes the multi-path input-output driver to determine that the at least one of the one or more initiators and the one or more targets used in the one or more of the input-output operations correspond to the at least one of the selected ones of the plurality of paths.
 20. The computer program product of claim 18 wherein the program code further causes the multi-path input-output driver to execute the management of the one or more of the input-output operations responsive to the count of events exceeding the threshold. 